High-absorption mineral-containing composition and foods

ABSTRACT

To provide a composition containing a mineral absorption accelerator which accelerates the absorption of minerals. It contains minerals and degradated products of poly- gamma -glutamic acid as a mineral absorption accelerator and may be used in foods in a variety of forms, including a beverage, gel, solid or powder form.

This application is a continuation of application Ser. No. 08/125,829,filed on Sep. 24, 1993, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a composition which has an acceleratedmineral-absorbing effect and foods containing it. More specifically, itrelates to a composition which contains minerals and poly-γ-glutamicacid degraded product as a mineral-absorbance accelerating additive, andfoods containing them.

2. Discussion of the Background

The human body comprises about 20 minerals, and of these Japanese peopletend to be deficient in calcium, iron, zinc, copper, magnesium and otherminerals, creating what is considered to be a dietary problem. Inparticular, the deficiencies are in calcium and iron.

In the case of calcium, the recommended daily allowances for adults hasbeen set at 600 mg, and while the national average intake per capita isslightly lower at 540 mg (1989 national nutrition survey), a reducedintestinal absorption rate of calcium due to a variety of causes has ledto the problem of calcium deficiency in the body. Osteoporosis, whichoccurs with high frequency among the elderly, is mainly related to abreakdown in the balance between calcium intake and excretion, and thisbecomes a major cause for the increase in bed-ridden elderly.Osteoporosis occurs with particularly high frequency amongpostmenopausal women, and one of the causes of this is thought to be theconsiderable lowering in secretion of female hormone (estrogen) and thelowering of the calcium absorption rate by the small intestine. Thenumber of osteoporosis patients is increasing year by year, and ispresently reported to be about 5 million.

In the case of iron, the recommended daily allowances for adults hasbeen set at 11 mg (10 mg for men, 12 mg for women), and the nationalaverage intake per-capita is 11.4 mg (1989 national nutrition survey),barely fulfilling the recommended daily allowances as an average for menand women, while the problem of iron deficiency occurs particularlyamong menstruating women. It has been calculated that menstruating womenexcrete about twice the amount of iron per day as adult males, and thusthe balance of iron in the body tends towards a lack thereof. Theresults of surveys reveal that 40-60% of menstruating women suffer fromiron deficiency anemia.

Generally, it is considered that minerals must be present in the smallintestine in a soluble state in order to be absorbed.

In the case of calcium, there are two routes for absorption, activetransport controlled by the regulation of vitamin D and various hormoneswhereby calcium is absorbed in the upper small intestine against aconcentration gradient, and passive transport whereby calcium in thelower small intestine is absorbed following a concentration gradient.However, when calcium is present in large amounts in the intestine, suchas during the intake of food, the proportion of the passive transportfrom the lower small intestine is overwhelmingly high, and in contrastto the case of the active transport which cannot rise above a certainamount even if the concentration of calcium increases, the passivetransport rises as the amount of the soluble calcium concentration inthe intestine increases (Am. J. Physiol., 240, 32, 1981). In general,the rate of absorption of calcium in the intestines is reported to be10-50%.

Iron is mainly absorbed in the upper small intestine, through the twomodes of absorption of heme iron and nonheme iron. Whereas heme iron isabsorbed as an iron porphyrin complex, nonheme iron is solubilized andliberated as a free ion before being absorbed (Gastroent., 58, 647,1971). The absorption rate of iron is extremely low, being not greaterthan 10-20% for heme iron and 1%-5% for nonheme iron.

Casein phosphopeptide (CPP), a product of the enzymatic degradation ofthe milk protein casein, is an example of a substance which exhibits anaccelerating effect on the absorption of calcium and iron by raising theconcentrations of soluble calcium and soluble iron in the smallintestine (Japanese Patent Publication No. HEI 02-7616, Japanese PatentUnexamined Publication No. SHO 59-162843). Calcium and iron aremaintained in a soluble state by the chelating effect of the phosphategroups of phosphoserine and carboxyl groups of the acidic amino acidscontained in CPP, which is therefore reported to produce an absorptionaccelerating effect thereon by increasing the concentrations of solublecalcium and soluble iron in the small intestine. However, the industrialproduction of CPP requires complicated procedures such as enzymetreatment, etc. , and when added to food, its degradation proceeds evenfurther during the course of its movement through the small intestine,sometimes leading to a loss in its ability to solubilize minerals.

Even if casein is consumed directly, it is degraded enzymatically in theintestine, producing CPP, and therefore mineral absorption isaccelerated. However, in this case as well, the degradation is promotedin the intestine sometimes leading to a loss in its ability tosolubilize minerals, while casein has disadvantages from the point ofview of food processing, such as poor solubility (particularly in theacidic range), etc.

Furthermore, foods are sometimes mineral-enriched using inorganicmineral salts or mineral powders, but these have the possibility ofproducing insoluble salts with other copresent substances, and since theexcessive intake of one type of mineral inhibits the absorption of otherminerals, there is not much improvement in the utilization of mineralsin the body. For example, a large intake of calcium inhibits theabsorption of iron. Excessive mineral-enrichment of foods isdisadvantageous in that the taste of foods is spoiled by harsh,astringent, pungent taste produced by the minerals.

Poly-γ-glutamic acid, present in the viscous substance of natto orsecreted extracellularly by Bacillus bacteria such as Bacillus natto andthe like, and synthetic poly-α-glutamic acid, both possess asolubilizing effect on minerals in the lower small intestine andaccelerate mineral absorption (Japanese Patent Unexamined PublicationNo. HEI 03-30648) . However, when used as a material for food, sincepoly-α-glutamic acid is synthetic, there is a problem of safety, theproduction process is laborious, and like CPP it is sometimes degradedby proteases during movement through the intestine. Poly-γ-glutamic acidpresent in the viscous substance of natto or poly-γ-glutamic acidsecreted by Bacillus natto bacteria such as Bacillus natto under normalculturing conditions both have a high viscosity, and therefore the laborrequired during their preparation and food processing treatment has beena disadvantage.

SUMMARY OF THE INVENTION

The object of the present invention is to develop an ingredient whosepreparation is relatively simple, which has a favorable solubility forapplication in food processing, which may be used in a wide range offoods, and which maintains its activity in the small intestine, and todevelop thereby a composition which has an accelerating effect onmineral absorption while masking the extraneous taste of enrichedminerals.

Another object of the present invention is to provide a method foraccelerating the absorption of a mineral in a mammal.

Another object of the present invention is to provide a method foradministering a mineral to a mammal.

The objects of the present invention is provided for based on thediscovery that poly-α-glutamic acid can be degraded by proteases due tothe α-bond whereas poly-γ-glutamic acid cannot be degraded by proteasesdue to the γ-bond, that lowering the molecular weight of poly-γ-glutamicacid present in the viscous substance of natto or secreted by Bacillusnatto or the like under normal culturing conditions leads to its lowerviscosity and facilitates its preparation and food processing treatment,and therefor that poly-γ-glutamic acid degraded products of molecularweight 1×10⁴ - 3×10⁵ solubilize minerals in the small intestine and doesnot lose this solubilizing activity on minerals in the small intestineeven when added to foods. Furthermore, we have discovered thatpoly-γ-glutamic acid imparts a mellow taste to foods, while masking theharsh, astringent, pungent taste produced by enriched minerals, and as aresult of developmental research we have succeeded in developing acomposition by which minerals may be easily supplemented to the body,thus completing the present invention.

In other words, the present invention relates to a composition whichcontains minerals and poly-γ-glutamic acid degraded products as amineral absorption accelerator, and to foods which contain them and thushave an accelerating effect on the absorption of minerals.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features and attendant advantages of the presentinvention will be more fully appreciated as the same becomes betterunderstood from the following detailed description when considered inconnection with the accompanying drawings in which like referencecharacters designate like or corresponding parts throughout the severalviews and wherein:

FIG. 1 shows the relationship between the molecular weight (Mw) ofpoly-γ-glutamic acid, calcium concentration, and the viscosity ofpoly-γ-glutamic acid solutions.

FIG. 2 shows the results of measurement of the hemoglobin value inExample 8.

FIG. 3 shows the results of measurement of the hematocrit value inExample 8.

FIG. 4 shows the results of ⁴⁵ Ca amount in the portal blood in Example9.

FIG. 5 shows the results of ⁴⁵ Ca amount in the fumer in Example 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The minerals to be used according to the present invention include anyor all of the life-essential minerals, including calcium, iron,magnesium, zinc, copper, etc. Also, there is no restriction on the formof the mineral to be used, but chemically synthesized food additivessuch as calcium chloride, calcium citrate, calcium glycerophosphate,calcium gluconate, calcium hydroxide, calcium carbonate, calciumlactate, calcium pantothenate, dihydrogen calcium pyrophosphate, calciumsulfate, calcium triphosphate, calcium monohydrogen phosphate, calciumdihydrogen phosphate, etc. and natural calcium sources such as shellcalcium and bone calcium are preferred.

As for iron, chemically synthesized food additives such as ferricchloride, sodium ferrous citrate, iron citrate, ammonium iron citrate,ferrous gluconate, iron lactate, ferrous pyrophosphate, ferricpyrophosphate, ferrous sulfate and natural iron sources such as hemeiron are preferred.

The poly-γ-glutamic acid to be used according to the present inventionmay be poly-γ-glutamic acid extracted from the viscous substance ofnatto, or it may be poly-γ-glutamic acid secreted extracellularly ofbacteria belonging to the genus Bacillus, such as Bacillus natto,Bacillus licheniformis, Bacillus subtills, and Bacillus subtilis var.polyglutamicum etc. Also, there is absolutely no problem with includingthe levan contained in the viscous substance of natto or secretedsimultaneously by Bacillus natto. As bacteria are Bacillus natto ATCC15245, Bacillus licheniformis ATCC 9945A, Bacillus subtills NRRL B-2612,and Bacillus subtilis var. polyglutamicum etc. Natto, as describedabove, is a traditional fermentation food in Japan made of soy beans.There are also such kinds of soy bean fermentation foods in other Asiancountries, however, Natto is a wet and sticky food while the other foodsin the other Asian countries are the dry type. The ingredients whichgive the sticky characteristics to Natto are poly-γ-glutamic acid andlevan.

For the production of poly-γ-glutamic acid with the desired molecularweight, there is a method whereby the molecular weight ofpoly-γ-glutamic acid with a molecular weight higher than that desired islowered by an acid or by special enzymes not present in the intestines,which degrades γ-bonds, and a method whereby poly-γ-glutamic acid of thedesired molecular weight (1×10⁴ - 3×10⁵ as determined by the low anglelaser scattering meter method) is secreted by culturing Bacillus natto,etc.; however, there is no difference with using either source ofpoly-γ-glutamic acid.

Sources of suitable enzymes include the product of autolysis of bacteriasources which produce poly-γ-glutamic acid, Bacillus natto phage,Flavobacterium polyglutamicum, Aspergilus oryzae and enzyme extracts ofanimal tissue such a blood, brain, liver, spleen and kidney.

The poly-γ-glutamic acid preferably has a viscosity of from 4.2-2.2mPas, more preferably 2.54-2.44 mPas, when measured as a 2 mg/ml, 20 mMTris-HCl buffer, pH 7.2 solution using a digital rotational viscometermanufactured by Toyo Seiki, Inc.

Poly-γ-glutamic acid is usually obtained as a sodium salt, but there isno difference with using its other salts or the free polyglutamic acid.

If the composition is used as a food, such as a seasoning suitableexamples may be a Japanese-style seasoning such as soup stock or noodlebroth, table vinegar, sweet sake, miso, Worcester sauce, Chinese-styleseasoning mixtures, retort liquid seasonings, Western-style soup stock,pasta sauce, curry roux, retort curry, seasonings for seasonednon-coated frying and fried chicken, or fish flour for cooked rice andbase for boiled rice with tea, etc.

If the composition is used as a food, such as a processed meat or fishsuitable examples include, hamburger, meat balls, sausage, ham, boiledfish paste, chikuwa fish paste, fish balls, fish sausages, as well ascorned beef, beef cooked Japanese-style and boiled fish, oil-packed andother canned foods, and there is no problem with using eitherrefrigerated foods or frozen foods.

If the composition is used as a food, such as a processed oil or fat,suitable substances, may be any number of processed oils or fats whichdo not contain whole eggs, cryopreserved eggs, egg yolk or powdered eggwhite, and may include, for example, dressing, butter cream, animal orvegetable cream, shortening, margarine, chocolate, etc.

If the composition is used as a food, such as dairy product suitableexamples may be, cheese, processed cheese products, yogurt, white sauceand foods containing white sauce such as cream croquette, gratin, etc.

If the composition is used as a food, such as a beverage or soup whichdoes not contain polyphenol suitable examples are one which does notcontain polyphenol derived from fruit juice, coffee, tea, grape wine,etc. For example, the beverage may be refreshment beverages such asdairy beverages, lactic bacterium beverages, soybean milk, sportsdrinks, nutritional drinks, cider, etc. The soup may be a homogeneouspottage, consomme soup or Chinese-style soup which does not contain soygrains or cereal grains, and the high-absorption mineral-containingcomposition is contained in their liquid portion.

If the composition is used as a food, such as a confectionery suitableexamples are not a so-called bakery product such as cookies or pie, butmay be, for example, candy or caramel, as well as candy drops, sweetbean jelly, jellies which use gelatin or pectin, desserts which useagar, etc.

If the composition is used as a food, such as a cereal suitable examplesmay be, corn flakes, brown rice flakes, etc.

If the composition is used as a food, such as a flour-based food,flour-based food which is not a so-called bakery product or noodles, andmay be, for example, premixed flour such as vegetable pancake mix orsteam pan mix, rice cakes, crumbs, fen-tiao (sticks of bean jelly),hi-fun (rice flour-based noodles), shira-tama-ko (a bleaching powdermade from glutinous rice), jo-shinko (a confectionery stockmade fromnonglutinous rice), or Japanese confectioneries which use them.

An explanation will now be provided regarding the amounts ofpoly-γ-glutamic acid to be added according to the present invention.There is no limit on the proportion of poly-γ-glutamic acid to be added,but generally it may be added at about 0.1-10 wt % for dried foods and0.01-5 wt % for beverages based on the total weight of the food.

Minerals such as calcium and iron are simultaneously added forenrichment, and calcium is added to provide from 30 mg-300 mg, andpreferably 100 mg-200 mg of available calcium per serving for beverages,and 50 mg-3000 mg, and preferably 100 mg-1000 mg of available calciumper serving for gels, solids and flour granules, while iron is added at0.5 mg-100 mg, and preferably 1 mg-40 mg of available iron per servingfor beverages, and 1 mg-1000 mg, and preferably 2 mg-500 mg of availableiron per serving for gels, solids and flour granules.

When the composition is added to food products, it imparts a mellowtaste thereto and is able to mask the harsh, astringent, pungent tastecaused by reinforcement of minerals, and therefore even if the mineralsare reinforced in the foods to the above amounts, there is no effect atall on the taste of the foods.

The present invention also provides for a method of accelerating theabsorption of a mineral in a mammal, preferably a human, byadministering poly-γ-glutamic acid degraded products and said mineral.Administration may be oral or intravenous. In the case of oraladministration, this can be achieved by administering a mineral-enrichedcomposition such as one of the food compositions herein described. Suchfood compositions generally contain from 0.1-10 wt % poly-γ-glutamicacid for dried foods and from 0.01-5 wt % for beverages. The molecularweight of said poly-γ-glutamic acid is generally in the range of from1×10⁴ -3×10⁵.

The present invention also provides for a method of administering amineral to a mammal, preferably a human, by administeringpoly-γ-glutamic acid degraded products and said mineral. Administrationmay be oral or intravenous. In the case of oral administration, this canbe achieved by administering a mineral-enriched composition such as oneof the food compositions herein described. Such food compositionsgenerally contain from 0.1-10 wt % poly-γ-glutamic acid for dried foodsand from 0.01-5 wt % for beverages. The molecular weight of saidpoly-γ-glutamic acid is generally in the range of from 1×10⁴ -3×10⁵.

Having generally described this invention, a further understanding canbe obtained by reference to certain specific examples which are providedherein for purposes of illustration only and are not intended to belimiting unless otherwise specified.

EXAMPLE 1

Preparation of poly-γ-glutamic acid

To 500 g of commercially available wet natto (a traditional fermentationfood in Japan made of soy beans) was added 1,500 ml of distilled water,and after thorough washing and dissolution of the viscous substance, thebean portion was removed using a filtering cloth. The viscous filtratewas subjected to centrifugation separation, and the supernatant thereofwas adjusted to pH 2.0 using hydrochloric acid. After removal of theprecipitate by centrifugal separation, 150 g of sodium chloride wasadded thereto to precipitate the poly-γ-glutamic acid. After collectionof the precipitate by centrifugal separation, it was dissolved andneutralized in a sodium hydroxide solution. It was then dialyzed againstwater and lyophilized, to obtain 2 g of poly-γ-glutamic acid as a sodiumsalt. The molecular weight of the prepared poly-γ-glutamic acid wasmeasured with a low angle laser scattering meter (LALLS: Tosoh LS8000)and found to be 9.27×10⁵.

EXAMPLE 2

Degradeability of poly-α or -γ-glutamic acid by proteases

The results of investigation of the degradeability by proteases ofsynthesized poly-α-glutamic acid (molecular weight 80,000) and thepoly-γ-glutamic acid prepared in Example 1 above are shown in Table 1.The enzymes were added at 10 U per 1 mg of polyglutamic acid, and thereaction was conducted at 37° C. for 24 hours. Movement of the peak forpolyglutamic acid in gel filtration HPLC to the low molecular end ordisappearance altogether upon action of the enzyme led to the judgmentthat it had been degraded.

                                      TABLE 1                                     __________________________________________________________________________    Enzyme    Trypsin                                                                             Chymotrypsin                                                                         Pepsin                                                                            Elastase                                                                            Thermolysin                                                                          Pronase                                                                            Y8 Protease                                                                           Aspergillus              __________________________________________________________________________                                                         Protease                 poly-α-glutamic acid                                                              x     x      x   x     x      O    O       O                        poly-γ-glutamic acid                                                              x     x      x   x     x      x    x       x                        __________________________________________________________________________     (O: degraded; x: not degraded)                                           

EXAMPLE 3

Lowering of molecular weight of poly-γ-glutamic acid

The poly-γ-glutamic acid prepared in Example 1 was dissolved to aconcentration of 2 mg/ml, and the solutions were adjusted to pH 1 withhydrochloric acid, and then heated at 50° C. or 70° C. for 30 minutes to6 hours. After heating, the solutions were returned to room temperatureand then neutralized with a sodium hydroxide solution, dialyzed againstwater and lyophilized. The molecular weights of the resultingpoly-γ-glutamic acid degradated products were measured by LALLS, and theresults are shown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________                   Sample 1                                                                           Sample 2                                                                           Sample 3                                                                           Sample 4                                                                           Sample 5                                                                           Sample 6                                                                           Sample 7                                                                           Sample                      __________________________________________________________________________                                                      8                           Temperature (°C.)                                                                     --   50   50   50   50   70   70   70                          Time (hr)      --   0.5  2    4    6    1    3    5                           Molecular weight (Da) × 10.sup.4                                                       92.7 30.3 8.80 4.78 3.30 1.50 0.420                                                                              0.256                       __________________________________________________________________________

EXAMPLE 4

Calcium solubilization test

For each poly-γ-glutamic acid solution prepared in Example 3 (1 mg/ml),0.5 ml was premixed with 0.5 ml of 10 mM calcium chloride solution, andthen 1.0 ml of 20 mM phosphate buffer solution of pH 7 or 8 was addedthereto, and the solutions were incubated at 37° C. for 2 hours and thensubjected to centrifugal separation. The resulting calcium phosphateprecipitate was removed, the concentration of calcium in the supernatantwas measured by the atomic absorption method, and the rate of residuewas determined with the remaining calcium as soluble calcium. As acomparison, the same test was conducted using distilled water. Theresults are shown in Table 3 and FIG. 1 (results at pH 8) .

                                      TABLE 3                                     __________________________________________________________________________    Rate of residue of soluble calcium (%)                                        Sample 1 Sample 2                                                                           Sample 3                                                                           Sample 4                                                                           Sample 5                                                                           Sample 6                                                                           Sample 7                                                                           Sample 8                                                                           Distilled water                   __________________________________________________________________________    pH 7.0                                                                            32.6 27.8 26.8 27.1 27.2 32.6 20.4 13.5 7.3                               pH 8.0                                                                            52.6 45.3 42.2 42.8 44.4 48.6 30.3  7.9 1.1                               __________________________________________________________________________

EXAMPLE 5

Measurement of viscosity

The viscosities of each poly-γ-glutamic acid solution prepared inExample 3 (2 mg/ml, 20 mM Tris-HCl buffer, pH 7.2) were measured using adigital rotational viscometer manufactured by Toyo Seiki, Inc. This waseffected at a temperature of 23° C. and a rotation speed of 60 rpm(rotor: HM-1). The results are shown in Table 4 and FIG. 1.

                                      TABLE 4                                     __________________________________________________________________________             Sample 1                                                                           Sample 2                                                                           Sample 3                                                                           Sample 4                                                                           Sample 5                                                                           Sample 6                                                                           Sample 7                                                                           Sample 8                          __________________________________________________________________________    Viscosity (mPas)                                                                       16.9 4.20 2.54 2.43 2.24 2.44 2.35 2.20                              __________________________________________________________________________

EXAMPLE 6

Masking of extraneous taste of calcium

The masking effect of the astringent, pungent taste of calcium, upon theaddition of the poly-γ-glutamic acid degradated product prepared inExample 3, Sample 2 to calcium chloride solutions (0.5%, 1.0%, 2.0%) toamounts of 0.25% and 0.5% were determined by a panel of 4 people. In theevaluation, an astringent pungent taste which was strongly noticeablewas assigned 4 points, noticeable was assigned 3 points, slightlynoticeable was assigned 2 points, and unnoticeable was assigned 1 point.The averages of the results from the 4 people are shown in Table 5.

                  TABLE 5                                                         ______________________________________                                                       CaCl.sub.2 solution (%)                                        Poly-γ-glutamic acid (%)                                                                 2.0        1.0    0.5                                        ______________________________________                                        0                4.0        4.0    3.5                                         0.25            3.75       3.0    2.25                                       0.5              3.25        2.25  1.75                                       ______________________________________                                    

EXAMPLE 7

Masking of extraneous taste of iron

The masking effect of the astringent, extraneous taste (thecharacteristic blood-like taste of iron) of iron upon the addition ofthe poly-γ-glutamic acid degradated product prepared in Example 3,Sample 2 to ferrous sulfate solutions (0.1%, 0.5%, 1.0%) to amounts of0.25% and 0.5% were determined by a panel of 4 people. In theevaluation, an astringent, extraneous taste which was stronglynoticeable was assigned 4 points, noticeable was assigned 3 points,slightly noticeable was assigned 2 points, and unnoticeable was assigned1 point. The averages of the results from the 4 people are shown inTable 6.

                  TABLE 6                                                         ______________________________________                                                       FeSO.sub.2 solution (%)                                        Poly-γ-glutamic acid (%)                                                                 1.0       0.5    0.1                                         ______________________________________                                        0                4.0       4.0    2.5                                         0.25             3.0       2.75   1.5                                         0.5              2.5       1.75   0.75                                        ______________________________________                                    

It is clear from the above experiments that poly-γ-glutamic acids withmolecular weights of 1×10⁴ - 3×10⁵ possess the ability to solubilizecalcium, while having a low viscosity and protease resistance, and thatit masks the extraneous taste of calcium and iron. That it possesses theability to solubilize calcium in the small intestine as well is clearfrom Japanese Patent Unexamined Publication HEI 03-3648, and thus it isshown that poly-γ-glutamic acids of molecular weights 1×10⁴ -3×10⁵accelerate the absorption of calcium in the small intestine.

Regarding minerals other than calcium, poly-γ-glutamic acid has asexpected the same accelerating effect on solubilization thereof in thesmall intestine, and therefore accelerates their absorption in the smallintestine.

EXAMPLE 8

Iron absorption test

Just-weaned male Wistar rats (body weight about 50 g) were pre-raisedfor 3 weeks on iron-deficient feed (20% casein diet, iron content 3 ppm). At the end of the 3 weeks, blood was taken from the caudal vein, andthose rats with a hemoglobin value of 7 g/dl or lower were used asanemic rats, and provided for the following experiment. The anemic ratswere divided into 4 groups (8 rats per group), further given the abovementioned iron-deficient feed, and further raised for 6 weeks (only onegroup was given a standard feed (iron content 150 ppm) Also,preparations containing 1 ml of the feeds listed in Table 7 dissolved indistilled water were given orally each morning. The improving effect onthe anemia was judged by taking blood from the caudal vein once a weekand measuring the hemoglobin value and hematocrit value. The results areshown in Table 8 and FIGS. 2 and 3.

                  TABLE 7                                                         ______________________________________                                                                               Iron                                   Group Feed       Sample  Dosage        dosage                                 ______________________________________                                        1     Iron-deficient                                                                           H.sub.2 O                                                                             1    ml/day      0 μg                                   feed                                                                    2     Iron-deficient                                                                           FeSO.sub.4                                                                            250  μg/ml/day                                                                             50 μg                                   feed                                                                    3     Iron-deficient                                                                           FeSO.sub.4                                                                            250  μg(FeSO.sub.4)                                                                        50 μg                                   feed       -PGA    +35  μg(PGA)/ml/day                               4     Standard   H.sub.2 O                                                                             1    ml/day      0 μg                                   feed                                                                    ______________________________________                                         PGA = poly γ-glutamic acid according to Example 3, Sample 2        

                                      TABLE 8                                     __________________________________________________________________________    After 3 weeks               After 6 weeks                                     Group                                                                             Hemoglobin value (g/dl)                                                                    Hematocrit value (%)                                                                     Hemoglobin value (g/dl)                                                                    Hematocrit value                     __________________________________________________________________________                                             (%)                                  1    5.1 ± 0.5.sup.2                                                                        20.4 ± 3.0.sup.2                                                                       4.9 ± 0.5.sup.1,2                                                                      19.1 ± 1.8.sup.1,2                2    6.3 ± 0.7.sup.2                                                                        20.9 ± 1.9.sup.2                                                                       7.3 ± 0.6.sup.2                                                                        30.0 ± 3.2.sup.2                  3   11.2 ± 0.9.sup.1                                                                        42.8 ± 4.3.sup.1                                                                      14.6 ± 2.2.sup.1                                                                        52.3 ± 5.4.sup.1                  4   14.9 ± 1.5.sup.1,2                                                                      58.5 ± 6.1.sup.1,2                                                                    15.4 ± 2.3.sup.1                                                                        57.3 ± 4.5.sup.1                                                           (Average ± SD)                    __________________________________________________________________________     .sup.1 Significant difference for Group 2                                     .sup.2 Significant difference for Group 3                                

The above results prove that, since the polyglutamic acid acceleratesthe absorption of iron, the improving effect on the anemic Group 3provided a restoration to the same levels as Group 4 which was given thestandard feed.

EXAMPLE 9

Accelerating effect on calcium absorption

Five-week-old male Wistar rats (body weight about 130 g) were dissectedat the abdomen under nembutal anesthesia, and 8 cm of the ileum (at 12cm - 20 cm from the caecum) were ligated after washing and removing thecontents of the intestine. A solution containing 10 mM of CaCl₂, 10 μCiof ⁴⁵ CaCl₂, 20 mM of a phosphate buffer (pH 8.0) and 2 mg/ml of eachsample was injected into the ligated intestine, after which theintestine was returned into the abdominal cavity, and the rats wereallowed to remain at a controlled temperature of 37° C. Portal blood wastaken at 5, 15, 30 and 60 minutes after the injection, and the fumer wastaken at 30 and 60 minutes thereafter, and the respective amounts of ⁴⁵Ca were determined with a liquid scintillation counter.

    ______________________________________                                        Control Example 1                                                                         Distilled water                                                   Control Example 2                                                                         CPP (CPP-III, product of Meiji Seika, Inc.)                       Test Example 1                                                                            poly-γ-polyglutamic acid                                                (molecular weight 3 × 10.sup.5)                             ______________________________________                                    

The results from the portal blood are shown in FIG. 4, and the resultsfrom the fumer are shown in FIG. 5. It is confirmed from FIGS. 4 and 5that poly-γ-polyglutamic acid has an accelerating effect on theabsorption of calcium in the intestine even better than that observedfor casein phosphopeptide (CPP).

EXAMPLE 10

Application in foods

Foods containing the poly-γ-glutamic acid degradated product prepared inSample 2 of Example 3 and the results of the organoleptic testsconducted therefor will now be presented.

    ______________________________________                                        [10-1 Curry] Composition of curry (8 person portion)                          ______________________________________                                        Flour                   125    g                                              Butter                  100    g                                              Curry powder            20     g                                              Sodium poly-γ-glutamate                                                                         8      g                                              Calcium carbonate       4      g                                              Beef                    400    g                                              Onion                   600    g                                              Butter (for frying)     q.s.                                                  Potato                  300    g                                              Carrot                  150    g                                              Water                   1400   ml                                             Seasoning               q.s.                                                  ______________________________________                                    

Butter was melted in a frying pan and flour was placed therein to makebrown roux, and then the curry powder, poly-γ-glutamic acid and calciumcarbonate were added thereto and cooked slightly to make curry roux. Thebeef was cut into mouthsize pieces, fried in butter, and then water wasadded thereto for stewing. At this point, the previously prepared curryroux was slowly added thereto, and the mixture was stewed on low flamefor 30 minutes. The curry prepared in this manner was apportioned intoretort packs for retort sterilization. This curry contains approximately200 mg of calcium per serving, and since poly-γ-glutamic acid isingested therewith, the calcium of such curry is absorbed into the bodyin an efficient manner. Also, there was no difference in taste, feel orsmell even when compared to control foods which did not containpoly-γ-glutamic acid and calcium carbonate.

    ______________________________________                                        [10-2 Hamburger] Composition of hamburger                                     ______________________________________                                        Beef                    700 g                                                 Pork                    300 g                                                 Onion                   200 g                                                 Whole egg               150 g                                                 Bread flour             150 g                                                 Seasoning               20 g                                                  Spice                   4 g                                                   Sodium poly-γ-glutamate                                                                         0.762 g                                               Calcium carbonate       5 g                                                   ______________________________________                                    

Using the above composition, chopped beef and pork, minced and friedonion and the other materials were mixed well with a mixer, and thenformed into 10 aliquot, and frozen at -18° C. to prepare raw frozenhamburger. The prepared hamburger contained 0.05% (by weight) of sodiumpoly-γ-glutamate, and each hamburger contained 200 mg of calcium. Thiscorresponds to about 1/3 of the recommended daily allowances of calcium,and since it is consumed with poly-γ-glutamic acid which accelerates itsabsorption, it was assumed to be absorbed efficiently in the body. Whenthe raw frozen hamburger was cooked, and compared to control foods whichdid not contain poly-γ-glutamic acid and calcium carbonate, the tastewas pleasant with no difference in feel, taste and smell compared to thecontrol foods.

    ______________________________________                                        [10-3 Boiled fish paste] Composition of boiled fish paste                     ______________________________________                                        Frozen ground fish      1100 g                                                Soy protein             160 g                                                 Seasoning               30 g                                                  Sugar                   40 g                                                  Sweet sake              40 g                                                  Potato starch           100 g                                                 Water                   660 g                                                 Sodium poly-γ-glutamate                                                                         10 g                                                  Calcium carbonate       20 g                                                  ______________________________________                                    

The ground fish and other ingredients were combined, ground with tablesalt, molded and heated to obtain boiled fish paste. The obtained fishpaste was characterized by containing an abundant amount of easilyabsorbable calcium.

    ______________________________________                                        [10-4 Cream croquette] Composition                                            ______________________________________                                        Flour                   100 g                                                 Butter                  100 g                                                 Water                   600 g                                                 Milk                    900 g                                                 Seasoning               10 g                                                  Minced meat             100 g                                                 Sodium poly-γ-glutamate                                                                         1.18 g                                                ______________________________________                                    

To 100 g of butter was added 100 g of flour and the mixture was stirredand heated to make roux, after which the other materials were addedthereto, and the mixture was heated and kneaded to make white sauce,which was then cooled to normal temperature. A coating was placed onthis and portions were placed into heated oil and deep fried until thesurface became light brown. Each croquette (about 30 g) containedapproximately 15 mg of calcium due to the milk, and sincepoly-γ-glutamic acid was also contained therein, the ingested calciumwas assumed to be efficiently absorbed into the body. These comparedfavorably to control foods which contained no poly-glutamic acid, withrespect to feel, taste and smell. [10-5 Pottage soup]

One gram of sodium poly-γ-glutamate was added to smooth pottage soup(containing strained vegetables, potatoes, etc.) to 0.05%, 2% methylcellulose was added thereto, as well as bone calcium (baked calcium) toproduce a calcium content of 0.075%, and a spray-type granulator wasused to make granulated pottage soup base. When this pottage soup basewas dissolved in hot water to make pottage soup, one serving (120 ml) ofsoup contained 90 mg of calcium, since poly-γ-glutamic acid is ingestedtherewith, the calcium of such soup is absorbed into the body in anefficient manner. Also, there was no loss in smoothness, taste or smellwhen compared to control foods which did not contain poly-γ-glutamicacid or bone calcium. [10-6 Sweet bean jelly]

A 2.6 g portion of agar was soaked in water and allowed to absorbsufficient water, after which it was washed and dehydrated, torn intosmall bits and placed into a pot into which 72 ml of water was added,and then the mixture was heated and mixed, until the agar fullydissolved. Also, 180 g of sugar, 6 g of sodium poly-γ-glutamate and 10 gof ferrous sulfate were added thereto and the mixture was heated toboiling, and after straining with a sieve, the filtrate was againboiled, 110 g of raw bean jam was added thereto, and the mixture waskneaded. This was poured into a can or other mold while still warm andallowed to cool and solidify to prepare sweet bean jelly. This sweetbean jelly exhibited no extraneous taste of iron.

    ______________________________________                                        [10-7 Candy] Composition of candy                                             ______________________________________                                        Granulated sugar      4000   parts                                            Water                 1200                                                    Malt syrup            1000                                                    Poly-γ-glutamic acid                                                                          6.2                                                     Calcium gluconate     77.4                                                    Flavoring             10                                                      ______________________________________                                    

The sugar and water were placed in a thick copper pot, and upon boilingthe malt syrup was added thereto and the mixture was boiled to about150° C. After the poly-γ-glutamic acid and calcium gluconate were addedthereto and thoroughly mixed therewith, the pot was taken off the flameand the flavoring was added. This was molded and cooled to obtain hardcandy. This candy contained calcium and poly-γ-glutamic acid and theconsumed calcium was assumed to be efficiently absorbed into the body.

    ______________________________________                                        [10-8 Jelly] Composition of milk jelly                                        ______________________________________                                        Powdered gelatin        10     g                                              Sugar                   80     g                                              Milk                    400    cc                                             Sodium poly-γ-glutamate                                                                         2.5    g                                              Vanilla essence         q.s.                                                  ______________________________________                                    

The powdered gelatin was poured onto 4 tablespoons of water and allowedto swell. The sugar and gelatin were added to the milk, the mixture wasput on flame and dissolved with slight mixing, and just before boilingthe flame was extinguished and the vanilla extract was added thereto.The mixture was poured into a mold and cooled to obtain milk jelly. Thismilk jelly contained abundant calcium due to the milk, and since it wasingested with poly-γ-glutamic acid, the calcium was assumed to beefficiently absorbed into the body.

    ______________________________________                                        [10-9 Skewer dumplings] Composition of dumplings                              ______________________________________                                        Jo-shin-ko              400    g                                              Shira-tama-ko           80     g                                              Lukewarm water          300    ml                                             Sodium poly-γ-glutamate                                                                         3.9    g                                              Calcium carbonate       3.12   g                                              ______________________________________                                    

Lukewarm water was added to the above composition, and the mixture wasthoroughly kneaded. The resulting dumpling seeds were placed together ina steamer, and steamed on high flame for 20 minutes. After steaming theywere taken out while still hot, placed in water to cool, and thenmassaged well with a damp cloth. This was formed into bite-sizedportions and pierced with skewers, and then dipped in soup consisting ofsugar and soy sauce or, strained bean jam to obtain skewer dumplings.These skewer dumplings contained poly-γ-glutamic acid, and therefore theingested calcium was expected to be efficiently absorbed into the body.[10-10 Vegetable pancakes]

To 500 g of vegetable pancake premixed powder containing mostly flourwere added 2.5 g of sodium poly-γ-glutamate and 5.0 g of bone calcium,and the materials were thoroughly mixed. Water, egg, vegetables and meatwere added thereto, and dissolved, after which the mixture was fried ona heated and greased iron hotplate to obtain vegetable pancakes. Thesevegetable pancakes contained calcium and poly-γ-glutamic acid, andtherefore the ingested calcium was assumed to be efficiently absorbedinto the body.

The present invention provides for a composition containing minerals anda mineral absorption accelerator, as well as to foods which containthem, and upon ingestion thereof the concentration of soluble mineralsin the intestine is increased, thus the absorption of minerals isaccelerated, thus offering the effects of mineral enrichment for growingchildren, prevention of bone disease typified by osteoporosis in theelderly, and avoidance of mineral unbalances which occur even in healthypeople due to a high-protein diet, high-phosphate diet, etc.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. A mineral-enriched composition comprisingi) 0.1to 10 wt %, based on the total weiqht of the composition, ofpoly-γ-glutamic acid degraded products of molecular weight 1×10⁴ - 3×10⁵; and ii) a mineral selected from the group consisting of calcium, iron,magnesium, zinc, copper and mixtures thereof; wherein said compositionis not a bakery product or noodles.
 2. The mineral-enriched compositionof claim 1 comprising 0.01-5 wt % of poly-γ-glutamic acid degradedproducts, based on the total weight of the composition.
 3. The mineralcomposition of claim 1, wherein said mineral is calcium selected fromthe group consisting of calcium chloride, calcium citrate, calciumglycerophosphate, calcium gluconate, calcium hydroxide, calciumcarbonate, calcium lactate, calcium pantothenate, dihydrogen calciumpyrophosphate, calcium sulfate, calcium triphosphate, calciummonohydrogen phosphate, calcium dihydrogen phosphate, shell calcium,bone calcium and a mixture thereof.
 4. The mineral composition of claim1, wherein said mineral is iron selected from the group consisting offerric chloride, sodium ferrous citrate, iron citrate, ammonium ironcitrate, ferrous gluconate, iron lactate, ferrous pyrophosphate, ferricpyrophosphate, ferrous sulfate, heme iron and a mixture thereof.
 5. Afood comprisingi) a mineral-enriched composition according to claim 1 orclaim 2; and ii) an edible substance.
 6. The food of claim 5, whereinsaid food is selected from the group consisting of a liquid, powder andsolid seasoning.
 7. The food of claim 5, wherein said food is processedmeat or fish.
 8. The food of claim 5, wherein said food is processed oilor fat.
 9. The food of to claim 5, wherein said food is a dairy product.10. The food of claim 5, wherein said food is a beverage or soup whichdoes not contain polyphenol.
 11. The food of claim 5, wherein said foodis a confectionery but not a bakery product.
 12. The food of claim 5,wherein the food is a cereal.
 13. The food of claim 5, wherein said foodis a flour based food, but not a bakery product or noodles.
 14. A methodof accelerating the absorption of a mineral selected from the groupconsisting of calcium, iron, magnesium, zinc, copper and mixturesthereof in a mammal comprising administering poly-γ-glutamic aciddegraded products of molecular weight 1×10⁴ -3×10⁵ and said mineral tosaid mammal.
 15. A method of administering a mineral selected from thegroup consisting of calcium, iron, magnesium, zinc, copper and mixturesthereof to a mammal comprising administering poly-γ-glutamic aciddegraded products of molecular weight 1×10⁴ -3×10⁵ and said mineral tosaid mammal.